Utilizing vulcanized waste rubber



' UNITED STATESPATENT OFFICE.

s'rum'r .B. MOLONY,

UTILIZING vuLoemznD wns'rn RUBBER.

This invention relates to the utilization of vulcanized waste rubber containing cotton or other fabric such as the canvas or cord part of automobile tires, rubber belts, etc.

Such scrap is now utilized largely by first grinding it to allow easy penetration by v chemicals, and then through the destruction it to the action ofof the fiber by subjecting acids and alkalie's. The following invention relates to the utilization of such material by first :-converting it into hard rubber, and second :-either utilizing it as it is without separation of the fabric, or by thegrinding and separation of the fiber from the bar rubber dust through sifting, air. flotation, or other similar means. This is an improvement in the utilization I of scrap rubber containing fabric through its direct conversion into hard rubber by the absorption of sulfur without the cost of grinding or compounding, or changing its so form in any way, except to cut it or reduce it by other means to pieces of suitable size. The resulting hard rubber, with the fabric embeddedalso has the advantage over the original scrap in that because of its hardness it can be ground fine'to make possible mechanical means of separation fiber, and because of its greater specific gravity than soft rubber, it can be more easily separated from the fiber by flotation 40 after grinding. The fabric and hard rubber can also be subjected to sufficient heat to 1 weaken the fiber so it can be more easily I ground to a powder, if the separation of the hard rubber and the fiber is not desired.

In order to convert soft rubber scrap into hard rubber it is necessary to more sulfur, depending upon the amount 0 sulfur already present, and upon the results desired. In order to add this sulfur, and accomplis'hthe conversion of the vulcanized soft rubber fabric scrap into hard rubber without grinding it, I make use of the fact that sulfur enters into solution in rubber before vulcanization takes place, and also during vulcanization; and that like any mateterial going into solution it. w1ll diffuse into or wri LEsLnY HILLS,

Specification of Letters Patent.

sulfur,

in a mixing machine with pow .are subsequently heated,

add up to 32% the time of immersion,

- varying the mnssnciazusnrrs.

rubber to a slight degree. In addition to this property of diffusion, which, for the time required for vulcanization, is very limited, I makeuse of the capillary action of the fabric which actsas a wick to draw melted sulfur into intimate contact with the surrounding rubber, and to hold it as a reservoir, giving it up as it is needed, as vulcanization proceeds. In practice, when the production of ground hard rubber is the object, I prefer to cut the fabric containing rubber into pieces of fairly uniform size, such, for instance, as will go through an inch or an inch and a half screen. I then impregnate the contained fiber with sulfur either by immersing the pieces for a short time in melted orby mixing them in a mixing machine with melted sulfur, or by mixing them dered sulfur which will be sucked into the fiber when they other subject them to the requisite vulcanizing temperature in any convenient Way, and upon completion of the vulcanization, the time for which convenient way.

i will depend upon the temperature employed,

they are ready for grinding.

While I mention above pieces of considerable size I do not confine myself "to pieces of large size as the rubber can be reduced by suitable means to pieces so small that some of the fiber can be separated before the remaining fiber is impregnated with sulfur for vulcanization.

I find that in order to save sulfur and also in order to control the resulting product so that a semi-hard product may be produced if desired, it is desirable to control with some care the amount of sulfur used for imregnating the fiber contained in the pieces.

his can b controlled'in various ways.

the pieces are immersed. in melted sulfur for impregnating. the amount of the sulfur absorbed by the fiber, and the amount clinging to the outside ofthe pieces which will be drawn into the fiber as that already in it is used by the rubber as vulcanization proceeds, can be controlled by controlling the temperature of the sulfur, and so its vls'cosity, and also by ratio of thearea of the surface to the weight of the pieces coated.

If it is desiredtouti ize the material in large pieces in its original form without grinding, pleces of suitable size are impreg- Patented July 19, 1921. March 30,1918. Serial No. 225,803.

nated with the and vulcanized I claim:

' 1. The herein ducing hard rubber containing fabric from .soft vulcanized rubber containing fabric,

comprising impregnating with sulfur the contained fabric in the soft vulcanized rubber, and subjecting it to a vulcanizing temperature for a sufficient time to vulcanize the soft rubber hard.-

' 2. The herein described process of producin hard, or semiwhard rubber containing fa ric from soft vulcanized rubber containing fabric, comprising impregnating with sulfur the. contained fabric inthe soft vulcanized rubber, and subjecting it to a vulcanizing temperature for a sufficient time to vulcanize the soft rubber hard.

3. The herein described process of producing hard rubber containing fabric from soft vulcanized rubber containing fabric, comprising introducing-the necessary sulfur into the soft vulcanized rubber through the fabric by utilizing its capillary action to conduct the melted sulfur into the rubber, the subsequent diffusion of the sulfur to all parts of the rubber, and canizing temperature for a sufficient effect the change.

4. The herein described process of protime to ducing'hard rubber dust from soft vulcanized rubber containing soft rubber hard, and

pregnating the contained ized rubber containing'fabric, comprising reducing the soft rubber scrap to pieces, pregnating the contained fiber with sulfur, subjecting them to a vulcanizing temperature for a suflicient time-to vulcanize the grinding the resulting hard" rubber and fiber. v

5. The herein described process of producing hardrubber dust from soft Vulcan ized rubber containing fabric, comprising reducing the. soft rubber scrap to pieces, impregnating the contained fabric'with sulfur, subjecting them to a vulcanizing tempera-- ture for a sufficient time to vulcanize the soft rubber hard and also to Weaken the fiber of the fabric, and grinding the resulting hard rubber and weakened fiber.

6. The herein described process of pro ducing hard rubber dust from. soft,vulcan-. fabric, comprising scrap topieceS, im

reducing the soft rubber fabric with sulfur,

I subjecting them to a vulcanizing temperarubber hard, grinding ture for a sufficient time to vulcanize the soft the resulting hard from the hard rubber. described process of prosoft rubber ing fiber with sulfur, subjecting to a vulcanizing temperature for a suflicient time to the subjection to a vul rubber ,rubber and fiber, and separatingthe fiber 105 rubber and fiber, and separating the fiber he herein described process of proized rubber containing fiber, by reducing the scrap to small pieces, separating some of the fiber, impregnating theremainvulcanize thesoft rubber hard, and the resultin hard rubber and fiber,

8. Asa new article of manufacture hard rubber'containing fabric producedfrom soft vulcanized rubber containing fabric, by impregnating with sulfur the contained fabric in the soft vulcanized rubber, and subjectingv it to a. vulcanizing temperature for a sufficient time to vulcanize the soft rubber hard.

9. As a new grinding article of manufacture hard rubber dust containing fiber produced from soft vulcanized rubber containing fabric, produced by reducing the soft rubber scrap to pieces,impregnating the contained fabric with sulfur, subjecting them to a vulcanizing temperature for a sufficient time to vulcanize the soft rubber hard, and grind ingthe resulting hard rubber and fiber.

10. As a new article of manufacture hard dust containing fiber produced from soft vulcanized rubber containing fabric by reducing the soft rubber scrap to pieces impregnating the contained fabric with sulfur, subjecting them to a vulcanizing temperature for a sufficient time to vulcanize the soft rubber hard and also toweaken the fibers of the .fabric, and hard rubber and weakened fiber.

11. As a new rubber containing fabric by reducing the soft rubber scrap to'pieces, impregnating the contained fabric with sulfur, subjectinig themto a vulcanizing temperature for a su ficient length of time to vulcanize the soft rubber hard, grinding the resulting hard from the hard rubber.

12. As a new article of manufacture semihard rubber containing fabric produced from soft vulcanized rubber containing fabric, by impregnating with sulfur the contained fabric in the soft and subjecting to a vulcanizing temperature, for a sufficient time to vulcanize the soft rubber semi-hard.

"STUART BQMOLONY. in. at

6.0 ducing hard rubber dust from soft vulcangrinding the vresulting article of manufacture hard rubber dust produced from soft vulcanized vulcanized rubber, i 

